Design of uncertain displacement controlled velocity control system for hydraulic actuator

المجلة: Heliyon

سنة النشر: 2024

تاريخ النشر: 2024-01-01

Displacement-controlled systems have high efficiency and are widely used in industry. Accurate control of the actuator motion in hydraulic systems is usually a necessity in industrial applications such as the motion of control surfaces in fixed-wing airplanes for flight control as well as the aircraft brake systems. To address this need, the current study was conducted with the goal of developing a high-fidelity model to achieve precise control. This work focused on modeling a hydrostatic transmission that is used for controlling a linear actuator velocity. The flow entering the actuator was changed using a variable displacement pump. The study included examining the stability and performance of the open-loop system. Additionally, the study involved the design of the proportional-integral-derivative PID and H∞ controllers, followed by the analysis of the stability and performance of the closed-loop system with both controllers. Furthermore, the multiplicative uncertainty is taken into account and the robustness of the system is verified using controllers PID and H∞. In the current study,Uncertain parameters such as actuator efficiency, pump speed, and viscous friction coefficient were considered and allowed for a ±5% deviation from their stated values. Taking uncertainty into account ensures that the system performs properly even in case where the design parameters vary within the specified range. The system response is compared for the cases of open-loop system, closed-loop system with PID controller, and closed-loop system with H∞ controller. The results demonstrated that the open-loop system remains stable for real-world applications but shows insufficient performance in terms of input tracking and disturbance rejection. The introduction of the PID controller significantly enhanced the system's response to a reference input; however, its disturbance rejection capabilities in terms of overshoot and settling time were still unsatisfactory. The system equipped with the PID controller failed to meet the robustness requirements. Conversely, the utilization of H∞ controllers yielded superior responses and fulfilled the robustness criteria.

Evaluation of N-piperazinyl-2-furanylketone as a corrosion inhibitor for mild steel in 1 M HCl solution: Combined experimental and theoretical approach

المجلة: International Journal of Corrosion and Scale Inhibition

سنة النشر: 2024

تاريخ النشر: 2024-01-01

Steel corrosion in acidic environments, poses a formidable challenge with conventional inhibitors, often burdened by issues of toxicity, and environmental impact. This study, addresses this challenge, by investigating the suitability of N-piperazinyl-2-furanylketone (NPF) as a green inhibitor for mild steel in 1 M HCl, employing a combined experimental and theoretical approaches. NPF demonstrated an outstanding inhibition efficiency of 93.6% under optimal conditions with an inhibitor concentration of 0.5 mM, at 303 K, showcasing its potential as an environmentally friendly alternative. The efficacy of NPF aligns well with the Langmuir adsorption isotherm indicating a robust and specific interaction between NPF molecules and the steel surface. Further analysis revealed a positive correlation between inhibition efficiency and both immersion time and temperature, suggesting a gradual formation of a protective film on the metal surface. It is worth noting that increasing the temperature enhanced the effectiveness of the tested inhibitor, indicating a thermally activated adsorption process. Theoretical calculations using density functional theory (DFT) supported the experimental results and provided insight into the molecular interactions at the interface. The calculated electron transfer parameter highlighted the positive interaction between NPF and iron atoms enhancing the observed inhibition mechanism. The study, giving the energy of NPF to be green inhibitor corrosion, among others, depicts a very effective method that can be used for evaluating the mechanism and efficacy of these ecofriendly alternatives. Besides synthetic applications studies can also be designed on real world scenarios hence, also capable of optimizing the performances of NPF for bulk industrial productions. © 2024, Russian Association of Corrosion Engineers. All rights reserved.

Inhibition mechanism and corrosion protection of mild steel in hydrochloric acid using 2-hydroxynaphthaldehyde thiosemicarbazone (2HNT): Experimental and theoretical analysis

المجلة: International Journal of Corrosion and Scale Inhibition

سنة النشر: 2024

تاريخ النشر: 2024-01-06

This study explores the inhibitory properties of 2-hydroxynaphthaldehyde thiosemicarbazone (2HNT) on mild steel corrosion in 1 M hydrochloric acid. The investigation of adsorption and inhibition mechanisms employed weight loss analysis, scanning electron microscopy (SEM), and density functional theory (DFT) techniques. Adsorption parameters were derived using various theoretical approaches. Optimal inhibitive efficacy, reaching 93.88%, was observed at a concentration of 500.0 ppm for the inhibitor during a 10-hour immersion period at 303 K. The study further examined the impact of immersion durations (5, 10, 24, and 48 hours) and inhibitor concentrations (100–1000 ppm) at 303 K, revealing 10 hours as the optimum immersion time. Inhibition efficiency increased with rising inhibitor concentration and remained steady beyond 10 hours up to 48 hours. Temperature effects were explored for different inhibitor concentrations, with 10 hours identified as the optimal immersion time. The Langmuir adsorption isotherm model was employed to elucidate the adsorption inhibition mechanism. Changes in activation energy values indicated distinct interactions between inhibitor molecules and the mild steel surface. Scanning electron microscopy analyses confi0rmed inhibitor molecule adsorption and the formation of a protective film on the mild steel surface. The mild steel-inhibitor interaction was scrutinized through DFT, revealing a minimal energy gap between the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO). The experimental and theoretical findings demonstrated congruence, affirming the efficacy of 2-hydroxynaphthaldehyde thiosemicarbazone as a corrosion inhibitor for mild steel in hydrochloric acid.